扬子北缘南华系武当群锆石U-Pb年龄:对扬子北缘南华纪裂解模式的启示  

Zircon U-Pb age of Wudang Group:implication to the breakup model of North Yangtze Block during the Early Neoproterozoic

作　　者：孔令耀 杨成 李琳静 周峰 郭盼 陈超 KONG Lingyao;YANG Cheng;LI Linjing;ZHOU Feng;GUO Pan;CHEN Chao(Hubei Geological Survey,Wuhan 430034,Hubei,China;Hubei Research Center of Geological Exploration and Engineering Technology,Wuhan 430034,Hubei,China)

机构地区：[1]湖北省地质调查院,湖北武汉430034 [2]湖北省地质勘查工程技术研究中心,湖北武汉430034

出　　处：《地质通报》2022年第12期2224-2243,共20页Geological Bulletin of China

基　　金：中国地质调查局项目《湖北省15万长岗店幅(编号:H49E003020)、均川幅(H49E003021)、客店坡幅(H49E004020)、古城畈幅(H49E004021)、三阳店幅(H49E005021)区域地质调查》(编号:DD20160030);湖北省地质局项目《武当-桐柏-大别造山带重要地质过程及其资源效应研究》(编号:KJ2022-6)。

摘　　要：扬子北缘出露的武当群是南秦岭地区最重要的基底组成物质,记录了南秦岭最古老的物质信息。为探讨扬子北缘南华纪的地层序列与裂谷演化模式,对湖北随州地区武当群典型剖面上的碎屑岩和火山岩进行锆石U-Pb测年,确定了武当群的沉积层序,并结合武当、随州地区的武当群锆石年龄,认为武当地区武当群年龄较随州地区老30 Ma左右,显示扬子北缘的南华纪裂谷具有自西向东逐渐打开的“剪刀式”裂解特征。武当群碎屑锆石主要峰值年龄为722 Ma、759 Ma、820 Ma、2014 Ma和2445 Ma,与扬子陆块碎屑锆石的峰值具有较好的对应,指示了武当群与扬子陆块强烈的亲缘性,峰值2014 Ma则反映武当群可能有来自桐柏—大别地区的物源信息;722~759 Ma的峰值代表扬子北缘南华纪早期裂解最强烈的时期,该裂解事件可能是扬子北缘Rodinia超大陆裂解过程的体现。The Wudang Group exposed in the northern margin of Yangtze Block is one of the most important basement of South Qinling Orogen,and it records the oldest provenance information of South Qinling Orogen.In order to explore the stratigraphic sequence of Wudang Group and rift evolution model of Nanhua period in the northern margin of Yangtze Block,we dated the zircon U-Pb age of clasolite and volcanics from typical geological sections of Wudang Group in Suizhou area,and determined the sedimentary sequence of Wudang Group.Combined with the chronological information of Wudang Group in Suizhou and Wudang area from previous researches,we find that the stratigraphic age of Wudang Group in Wudang area is older about 30 Ma than the ages in Suizhou area,which shows that the rift during Neoproterozoic may be cracking gradually like a"scissor"from west to east in the northern margin of Yangtze Block.The main age peaks of detrital zircons from Wudang Group is about 722 Ma,759 Ma,820 Ma,2014 Ma and 2445 Ma,which has a good correlation with main age peaks of detrital zircons from Yangtze Block,suggesting that the main provenance of Wudang Group is coming from the Yangtze Block.The age peak of 2014 Ma shows there may be provenance information from Tongbai-Dabie area,and the age peak about 722~759 Ma represents the strongest period of breaking up in the northern margin of Yangtze Block,whick may be the embodiment of the Rodinia supercontinent break-up in the northern margin of Yangtze Block.

关 键 词：扬子北缘 武当群 锆石年龄 “剪刀式”裂解 地质调查工程 湖北 

分 类 号：P597.3[天文地球—地球化学] P62[天文地球—地质学]